Intracellular pH homeostasis through the extrusion of a proton by F₀F₁-ATPase is one of the key mechanisms used by lactic acid bacteria in response to acid stress, and also influences their post-fermentation acidification. In this study, the genotypic and phenotypic stability of a low post-fermentation acidification (LPA) mutant (designated as DGCC12411^m) of Lactobacillus plantarum DGCC12411 was assessed. Compared with its mother strain, the pH of DGCC12411^m in De Man, Rogosa, and Sharpe (MRS) broth after 48-h cultivation was 0.35 pH units higher. Incorporation of DGCC12411^m in yogurt stored at ambient temperature (ambient yogurt) showed a reduced post-fermentation acidification during storage at 25°C for 120 d. Whole-genome sequencing analysis showed a SNP mutation (GGT > GAT at positions 505 to 507) in DGCC12411^m, which resulted in the substitution of a highly conserved glycine residue by aspartic acid at the Walker A motif of the F₀F₁-ATPase α-subunit. However, degeneration of the LPA phenotype was observed after 5 passages of DGCC12411^m in MRS broth. Analysis of DNA sequencing on both the whole population and the isolates showed that a back mutation occurred at the SNP site (GAT changed back to GGT) over the passaging, and the reversion gradually increased from a ratio of 10.8% at P5 to 60.0% at P10. We also found that the LPA phenotype stability of DGCC12411^m was improved by supplementing 0.1 M potassium phosphate buffer to the growth medium as well as by reducing the inoculation rate of DGCC12411^m to 2% (vol/vol). Such LPA Lactobacillus strains have potential for use as starter cultures in fermented foods with less change in acidity during shelf-life storage.

F ₀ F ₁ -ATPase通过质子挤出产生的细胞内pH稳态是乳酸菌响应酸胁迫的关键机制之一，并且还影响其发酵后的酸化。在这项研究中，评估了植物乳杆菌DGCC12411的低发酵后酸化（LPA）突变体（命名为DGCC12411 ^m）的基因型和表型稳定性。与它的母菌株相比，德曼，罗戈萨和夏普（MRS）肉汤培养48小时后DGCC12411 ^m的pH高0.35个pH单位。纳入DGCC12411 ^m在常温下贮存的酸奶中（常温酸奶），在25°C下贮存120 d时，发酵后酸化降低。全基因组测序分析显示DGCC12411 ^m中存在SNP突变（GGT> GAT在505至507位），这导致F ₀ F ₁ -ATPase的Walker A基序上的高保守甘氨酸残基被天冬氨酸取代。α-亚基。然而，在DGCC12411 ^m传代5次后，观察到LPA表型的退化。在MRS汤中。对整个种群和分离株的DNA测序分析表明，在传代过程中，SNP位点发生了反向突变（GAT变回GGT），并且回复率从P5的10.8％逐渐增加到60.0％。 P10。我们还发现，通过向生长培养基中添加0.1 M磷酸钾缓冲液以及将DGCC12411 ^m的接种率降低到2％（体积/体积），可以改善DGCC12411 ^m的LPA表型稳定性。此类LPA乳酸菌菌株具有用作发酵食品中的发酵剂的潜力，在保存期中酸度变化较小。